How does the immune system protect us from disease?
Immune system is formed of certain cells called as leukocytes or WBCS. These cells are of different types specific for different functions. Some of these cells called macrophages kill and engulf microbes and prevent its invasion. Some of these cells called plasma cells produce antibodies which neutralises pathogens. Other class of these cells called T cells produce different protein molecules like perforins, lymphotoxins which make pathogens inactive.